The present invention relates to a flow completion system for producing oil or gas from a hydrocarbon well. More particularly, the invention relates to a controls bridge for providing communication between the tubing hanger component of the system and a remote service and control vessel.
A typical horizontal-type flow completion system comprises a wellhead housing which is installed at the upper end of a well bore, a tubing spool or tree which is connected to the top of the wellhead housing, and a tubing hanger which is suspended in the tubing spool and which supports at least one tubing string that extends into the well bore. The tubing spool includes a production outlet through which the well fluids are produced, an annulus outlet through which the annulus surrounding the tubing string may be accessed, and a number of valves for controlling flow through the production and annulus outlets. In addition, the tubing spool typically supports a number of service valves, such as chemical injection valves, for controlling the flow of service fluids into the well bore. In the event of a failure of a service valve, this arrangement requires that the tubing spool be retrieved in order to repair or replace the valve. Retrieval of the tubing spool, however, requires that the completion consisting of the tubing hanger and tubing string first be pulled, which is a costly and time consuming procedure.
The tubing hanger may comprise a number of service and control conduits to facilitate the communication of control signals or fluids from a remote control station or an external subsea control module to valves or other devices located in or below the tubing hanger. The control signals or fluids are conveyed via external service and control lines which are connected to the remote control station through a controls umbilical or to the subsea control module, which is usually mounted on the tubing spool, through a length of fixed piping. Each service and control line is connected to a corresponding service and control conduit typically via a radial penetrator which extends laterally through the tubing spool and into the tubing hanger. However, existing radial penetrators are subject to mechanical failure, and each radial penetration represents a potential leak path in the tubing spool through which well fluids may escape into the environment.
These and other disadvantages in the prior art are overcome in the present invention by providing a controls bridge for a flow completion system that comprises a wellhead housing which is installed at the top of a well bore, a tubing spool which is connected above the wellhead housing, a tubing hanger which is supported in the tubing spool and from which is suspended at least one tubing string that extends into the well bore, and a plurality of service and control conduits that extend generally vertically through the top of the tubing hanger and communicate with corresponding devices located in or below the tubing hanger. The controls bridge comprises a body portion, a connector assembly for securing the body portion to the top of the tubing spool and/or the tubing hanger, at least one first coupling member which is adapted to engage a second coupling member that is mounted in a corresponding service and control conduit, at least one third coupling member which is adapted to engage a fourth coupling member that is connected to a corresponding external service and control line, a bridge line which is connected between the first coupling member and the third coupling member, and an actuating mechanism for moving both the first coupling member into engagement with the second coupling member and the third coupling member into engagement with the fourth coupling member to thereby connect the external service and control line with its corresponding service and control conduit in the tubing hanger.
Thus, the present invention allows each device which is located in or below the tubing hanger to be connected to its corresponding external service and control line through the top of the tubing hanger. Consequently, the traditional need to make these connections via radial penetrations between the tubing spool and the tubing hanger is eliminated, and the potential leak paths and mechanical complexity posed by such radial penetrations are avoided. In addition, since the controls bridge is preferably the sole interface between the external service and control lines and the corresponding devices located in and below the tubing hanger, the controls umbilical can be connected directly to the controls bridge, or to a junction plate which is mounted on the tubing spool and which in turn is connected to the controls bridge via a jumper. This arrangement eliminates the need for numerous individual connections between the controls umbilical and the tubing spool. Consequently, the cost and complexity of the overall flow completion system are reduced and the installation and operation of the system are simplified in comparison to prior art systems.
In one embodiment of the invention, the controls bridge may comprise one or more valves for controlling fluid flow through one or more bridge lines. Thus, for example, one of the external service and control lines may function as a chemical injection line and the controls bridge may comprise a chemical injection valve for controlling the flow of chemicals from the chemical injection line, through a corresponding service and control conduit in the tubing hanger and into the well bore. In this manner, the need for separate service valves mounted on the tubing spool may be eliminated. Moreover, if one of the service valves should malfunction, it may be repaired or replaced simply by retrieving the controls bridge, thereby eliminating the need to pull the completion and retrieve the tubing spool for this purpose.
Furthermore, the controls bridge of the present invention may facilitate communication with the annulus surrounding the tubing string. Thus, one of the external service and control lines may function as an annulus line which is connected via the controls bridge to a service and control conduit that communicates with the tubing annulus. The annulus line may, for example, communicate through an umbilical to a surface vessel or other remote location to allow for monitoring and/or venting of annulus pressure during production. In addition, another service and control line may function as a crossover line which is connected to both the tubing annulus and the production outlet to facilitate circulation of fluids between the tubing annulus and the production bore. Moreover, the controls bridge may also comprise one or more annulus closure members to control flow through the annulus lines and crossover lines. By positioning the annulus closure members in the controls bridge instead of on the tubing spool or in the tubing hanger, these components can be replaced or repaired simply by retrieving the controls bridge instead of having to pull the completion or retrieve the tubing spool.
The controls bridge is preferably a lightweight assembly that may be installed and retrieved using a remotely operated vehicle (xe2x80x9cROVxe2x80x9d) or an ROV in combination with a surface deployed cable. Alternatively, the controls bridge may be installed and retrieved using a remotely operated tool (xe2x80x9cROTxe2x80x9d). Thus, if any of the components within the controls bridge requires servicing, the controls bridge can easily be retrieved without the need to disturb either the tubing spool or tubing hanger, and without the need for a large, expensive service vessel.
These and other objects and advantages of the present invention will be made apparent from the following detailed description, with reference to the accompanying drawings. In the drawings, the same reference numbers are used to denote similar components in the various embodiments.